Licences and source code

What Steerwell is built with

Steerwell is proprietary software by Black Ueli GmbH. To read recordings and cut clips, it runs FFmpeg, which includes LAME, as a separate program. Both are open source under the GNU Lesser General Public License (LGPL). Here is the exact source of the versions Steerwell 0.2.0 ships, and how they were built.

FFmpeg 9.0.2

Licence: LGPL version 2.1 or later. As published by the FFmpeg developers (ffmpeg.org), not modified, and built without GPL or non-free parts.

Source: ffmpeg-9.0.2.tar.xz · 12.0 MB
SHA-256: 8c3850283eb25fa026482078a04051e0be17347b09ef81a0849bec15a96e002e
Upstream: https://ffmpeg.org/releases/ffmpeg-9.0.2.tar.xz

LAME 3.100

Licence: LGPL version 2 or later. As published by the LAME project (lame.sourceforge.io); FFmpeg uses it to write MP3. Its code is not modified: the build only drops one symbol LAME doesn’t define from its list of exported ones, as shown below.

Source: lame-3.100.tar.gz · 1.5 MB
SHA-256: ddfe36cab873794038ae2c1210557ad34857a4b6bdc515785d1da9e175b1da1e
Upstream: https://downloads.sourceforge.net/project/lame/lame/3.100/lame-3.100.tar.gz

How they were built

On a Mac with Apple Silicon, for macOS 12.0 and later, linking only macOS’s own libraries. LAME is built first, as a static library, and FFmpeg is linked with it:

export MACOSX_DEPLOYMENT_TARGET=12.0
PREFIX=$PWD/prefix

tar xf lame-3.100.tar.gz
cd lame-3.100
sed -i '' '/^lame_init_old$/d' include/libmp3lame.sym
./configure --prefix=$PREFIX \
  --disable-shared \
  --enable-static \
  --disable-frontend \
  --disable-decoder
make && make install
cd ..

tar xf ffmpeg-9.0.2.tar.xz
cd ffmpeg-9.0.2
./configure --prefix=$PREFIX \
  --disable-autodetect \
  --disable-ffplay \
  --disable-ffprobe \
  --disable-doc \
  --disable-debug \
  --disable-network \
  --enable-videotoolbox \
  --enable-audiotoolbox \
  --enable-zlib \
  --enable-bzlib \
  --enable-iconv \
  --enable-libmp3lame \
  --extra-cflags=-I$PREFIX/include \
  --extra-ldflags=-L$PREFIX/lib \
  --extra-libs=-liconv
make
strip -o ffmpeg-steerwell ffmpeg

The app keeps the result in Steerwell.app/Contents/Resources/ffmpeg/ffmpeg. You may replace it with your own build: put it in its place, or name it in the STEERWELL_FFMPEG environment variable.

Everything else

The full licences of FFmpeg, LAME, Electron, Chromium and every other component Steerwell includes are in the app, under Help → Acknowledgements.